Gas-separating apparatus



Jan. 13, 1959 Filed July 2, 1954 J/VAN DER STER 2,867,985

GAS-SEPARATING APPARATUS 2 Sheets-Sheet l INVENTOR JOHANNES VAN DER STER Jan. 13, 1959 ,1. VAN DER STER 2,867,985

GAS-SEPARATING APPARATUS Filed July 2, 1954 I 2 Sheets-Sheet 2 INVENTOR JOHANNES VAN DER STER BY WM? United States Patent GAS-SEPARATIN G APPARATUS Johannes van der Ster, Eindhoven, Netherlands, assignor,

by mesne assignments, to North American lhlllps Company, Inc., New York, N. Y., a corporation of Delaware Application July 2, 1954, Serial No. 441,082

Claims priority, application Netherlands July 15, 1953 4 Claims. (CI. 62-40) This invention relates to gas-separating apparatus which comprise a fractionating column, from which heat is withdrawn by means of a gas refrigerator, and a boiling vessel, and in which atmospheric or substantially atmospheric pressure prevails where the gas mixture to be fractioned is supplied to the column. The term gas refrigerator is to be understood to mean a refrigerator operating according to the reversed hot-gas engine principle. As is known there are several types of such refrigerators, for example replacer apparatus, double-acting apparatus, apparatus of which the working chamber is combined with that of a hot-gas engine or apparatus whereof the cylinders are arranged in the form of a V.

With columns to which thegas mixture to be fractioned is supplied at a pressure in excess of the atmospheric pressure, it will generally be feasible, as a result of the pressure difference between the boiler and the atmospheric pressure, to expell from the boiler a part of the vapour fraction having the higher or highest boiling point.

If, however, the gas mixture to be fractioned is supplied at atmospheric or substantially atmospheric pressure, which may particularly be done when cold is derived from the column by means of a gas refrigerator, the pres sure in the boiler will, in general, be insufficient to expel the vapour. This will particularly be the case if the vapour expelled from the boiler is passed through a heat exchanger in which the vapour is in heat-exchanging contact with the gas mixture to be fractioned. The lastmentioned case often occurs in practice.

The present invention has for its object to provide a construction which permits the vapour fraction having the higher boiling point to be expelled from the boiler without having recourse to a pump or only with the use of a pump of low capacity.

In accordance with the invention the apparatus, between the area, where the gas mixture to be separated is supplied to the column, and the boiler offers such a resistance to flow to the vapour ascending from the boiler that part of the vapour is carried off, also as a result of the pressure difference produced by the flow-resistance between the boiler and the atmosphere. The term to carry 0 a fraction is to be understood to mean expulsion of a fraction from the apparatus. The required flow-resistance results from giving the column a suitable size and from a suitable filling. For example in the case of the column being filled with filling material, by means of a suitable choice of the dimensions of the filling material.

In one embodiment of the invention, a column comprises a wall arranged between the area where the gas mixture to be separated is delivered to the column and the boiler, provision being made of one or more ducts "ice connecting the column and the space above the liquid level in the boiler, which ducts have such a flow-resistance to the vapour rising through said duct(s) that a further part of the vapour is expelled from the boiler, also as a result of the pressure difference thus produced between the boiler and the atmosphere. Said wall may be provided at a suitable point. If it is placed in the column itself it should comprise one or more openings for the passage of the condensation liquid.

As an alternative, the bottom of the column may be used for this purpose. In this case, when there is a wall between the fractionating column and the boiler provision is made, in a further embodiment of the invention, of a duct, besides the ducts connecting the spaces below and above the wall, between the column and the boiler, which duct extends into the normal liquid level in the boiler and, during normal operation of the column, is at least partly filled with the liquid leaving the column.

In these constructions the required flow-resistance results from a suitable size of the ducts, so that in connection with the flow-resistance no particular requirements are imposed on the column itself.

In a simple construction, according to one embodiment of the invention, a duct passes through the wall between the column and the boiler and reaches into the liquid of the boiler.

In a further embodiment of the invention, the boiler is directly joined by the column and the partition between the column and the boiler comprises one or more openings for the vapour rising from the boiler, which openings have such a flow-resistance to the vapour that, also as a result of the pressure difference thus produced between the boiler and the atmosphere, a part of the vapour is expelled from the boiler.

In the aforesaid apparatus less vapour should be expelled upon a decrease in the production of cold by the cooler, whereas more vapour should be expelled upon an increase in production of cold. Therefore, in one embodiment of the invention, the gas mixture to be separated and at least a part of the fraction of the higher boiling point is supplied to the column or carried off in accordance with the production of cold by the gas refrigerator.

In a further embodiment of the invention said supply and exhaust in accordance with the production of cold is effected in a simple manner by condensation of the vapour rising from the column, a part of the condensation liquid being returned to the column and a further part being carried off through a duct comprising a liquid lock.

In order that the invention may be readily carried into effect, it will now be described in detail with reference to the accompanying drawings, given by way of example, in which Figs. 1 and 2 show diagrammatically a gas-fractionating apparatus according to the invention, of which Fig. 2 is a cross-sectional view on the line II-II of Fig. 1.

Fig. 3 shows on a larger scale a. gas refrigerator for use in this apparatus.

The apparatus shown in Fig. 1 comprises a fractionating column 1 made up of two parts 2 and 3 whereof the former is larger in diameter than the latter. The

extension of the bounding wall 4 of part 2 surrounds thev bounding wall 5 of the part 3 joined by the boiler 6, the two walls being separated by an annular space 7. The part 3 of the gas-fractionating column is separated from the boiler 6 by means of a wall 8 through which pass a tube 9 and a tube 10 through which the space and the 3 column and the boiler are connected with each other. The tube 10 reaches approximately to the bottom 11 of the boiler which comprises projecting parts. Said bottom has an opening 12 joined by a pipe 13. During operation the boiler contains a liquid quantity of the fraction having the higher boiling point, the pipe 13 protruding from the normal liquid level. At the lower side of the bottom the opening 12 is joined by a tube 14, hereinafter termed carrier. The carrier 14 externally comprises projections 15 provided with openings 16which are offset, as may be seen from Fig. 2. The carrier 14 comprises pro- -jectins 17 with openings 18. The projections 15 are surrounded by a shell 19 consisting of heat-insulating material and furnished with openings 20 and 21 at the lower side. The openings 20 are at one side joined by the spaces between the projection and at the other A side by a conduit 22. The opening 21 is joined by the tube 14 and by an outlet pipe 23. The annular space '7 is connected with the space between the projections 15.

At its upper end the column is connected through a conduit 24 to a gas refrigerator 25 which is shown on a larger scale in Fig. 3. The vapour escaping from the column is condensed by means of the refrigerator 25, the condensation liquid being collected in the annular gutter 26 furnished with two outlet pipes 27 and 28. The former is joined by the fractionating column and the condensation liquid delivered through it to the column acts as reflux. A further part of the condensation liquid is carried off through the conduit 28, which comprises a so-called liquid lock 29.

The operation of the apparatus is as follows. The gas mixture to be fractioned for example air, is supplied through the conduit 22 and, streams through the apertures past the projections 15. Thereby the gas mixture is cooled, any impurities, for example Water vapour and CO of the gas mixture being frozen out on the extensions. To this end the temperature difference between the successive projections should not be too large. They should, for example, not exceed 20 degrees centigrade. Moreover, the temperature of those projections, on which the deposit commences, should not be more than 20 degrees centigrade lower than the dew point of the water vapour contained in the air to be fractioned. For this purpose the carrier 14 should have a suitable flow-resistance.

The cooled air flows at atmospheric or substantially atmospheric pressure through the space 7 to the gasfractionating column where the air is divided into fractions. The boiler contains a liquid quantity of the fraction having the higher boiling point, for example oxygen, which is vaporized by the heat supplied through the carrier 14. The vaporized oxygen is replenished by the liquid rich in oxygen descending from the column into the tube 10. A part of the vaporizing oxygen is supplied through the tube 9 to the column. A further part is removed from the boiler through the tube 13, the support 14 and the pipe 23. As a result of the partition 8 with opening 9 the column offers flow-resistance to the rising vapour so as to produce, while the column operates at atmospheric pressure or substantially atmospheric pressure, a considerable pressure difference between the boiler and the area where the medium to be fractioned is supplied to the column with the result that said fraction is carried off due to the pressure difference between the boiler and the atmosphere. This requires the flow-resistance of the tube 13, the carrier 14 with the projections 17 and of the tube 23 to be overcome.

.In the apparatus shown in the drawing, the air to be fractioned is supplied by means of the sub-atmospheric pressure produced by the liquid lock. The liquid level setting in the conduit 28 is just sufficient to supply the air to be fractioned. The ratio between the quantity of condensation liquid supplied to the column and the quantity of'condensation liquid carried off through the conduit 28 is constant. The smaller the quantity of air supplied to the column, the smaller will be the quantity of vapour removed from the boiler in this apparatus. The medium to be fractioned and the fractions formed are delivered to the column or carried off in accordance with the heat withdrawn from the column.

In Fig. 3 the refrigerator is shown on a larger scale than in Fig. 1. As is known these refrigerators may be replacer apparatus, double-reacting apparatus, apparatus whereof the cylinders are arranged in the form of a V and apparatus whereof the working space is associated with that of a hot gas engine. Such apparatus permit temperatures of say --200 degrees Centigrade to be attained in one stage.

The apparatus used in this example is a replacer machine comprising a cylinder 30 wherein a displacer 31 and a piston 32 reciprocate. To this end the displace: 31 is coupled through a connecting rod mechanism 33 to a crank 34 of a crankshaft 35, the piston 32 being coupled through a connecting rod mechanism 36 to cranks 37 of the same crankshaft 35. The cranks 34 on the one hand and the crank 37 on the other hand subtend an angle of, say, degrees so that the piston and the displacer reciprocate with a constant phase difference. he space 33 above the displacer 31 is the so called freezing space which is connected with a space 42, the cooled space, through a freezer 39, a regenerator 4i and a cooler 41.

The medium to be cooled by the gas refrigerator is supplied to a space 45 through an opening 43 of a heatinsulating jacket 44. In the space 45, the medium is cooled so as, for example, to condense a vapour. A part of the condensation liquid may be carried off through a duct 46, for example to a gas-fractionating column, and a further part may be removed from the apparatus through a duct 47.

What is claimed is:

l. A gas separating apparatus comprising a fractionating column having an insulating outer jacket and including a boiler, a cold-gas refrigerator for withdrawing heat from said gas separating apparatus including a freezer and a condensor surrounding said freezer, means ma ntaining a sub-atmospheric pressure in said condensor ncluding a first outlet for condensed fluid provided wlth a liquid lock therein, a second outlet for condensed fluid connected to said column, and an inlet for said column wherein a gas mixture to be fractionated is drawn into said column at substantially atmospheric pressure due to the presence of sub-atmospheric pressure in said condensor, a tube in said boiler for expelling at least part of the vapor present in said boiler, means provided between the boiler and part of said column for causing a flow resistance to the rising vapors in said boiler whereby a pressure is built up in said boiler sufficient to expel said part of the vapor through said tube.

2. A gas separating apparatus as claimed in claim 1 further comprising a wall separating the boiler and the other part of said fractionating column, a duct passing through said wall being so dimensioned as to provide said flow resistance to the rising vapors in said boiler.

3. A gas separating apparatus as claimed in claim 2 wherein said tube is provided with a plurality of spaced projections, said projections having openings therein, said inlet for said column being operatively connected to said projections whereby said gas mixture is introduced through said inlet and follows a path through at least part of the apertures on said projections to said fractionating column.

4. A gas separating apparatus as claimed in claim 1 further comprising a wall separating said boiler and the part ofsaid fractionating column above said boiler,

aconduit extending through said wall and extending below the liquid level in said boiler.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Levy May 3, 1910 Levy May 31, 1910 Claude Aug. 9, 1910 Claude July 22, 1913 Claude Jan. 13, 1914 Claude Nov. 25, 1919 Van Nuys Dec. 30, 1924 Wilkinson May 26, 1925 6 Schlitt May 14, 1935 Schlitt Apr. 2, 1940 Schlitt July 30, 1940 Dennis Aug. 22, 1950 Taconis Sept 11, 1951 Benedict Feb. 10, 1953 FOREIGN PATENTS France Apr. 11, 1911 France July 29, 1915 Great Britain Aug. 13, 1946 

